Major transformations in family behavior (marriage, cohabitation, divorce, childbearing and the use of child care centers) have occurred in the United States and other developed countries. These family behavior changes occurred in a context of major structural changes in the economy, education and other institutions, along with changes in the attitudes of individuals towards many components of what had been the traditional family institution. The implications of these changes have been profound, for both the family system (e.g. children growing up in single parent families) and other institutions (e.g. the link between low fertility and old- age support systems). The changes in family behavior have been well documented, but the processes that led to such dramatic changes are still not well understood. Building upon an existing cross-sectional data set, the proposed research will collect and build a data set that is specifically designed to address the interplay of structural societal change, individual behavior and attitudes, and the emergence of an altered family institution in a country, Japan, where many of these family behavior changes began recently, thus affording a chance to examine the processes that facilitate broad-scale family behavior change. After a series of theoretically informed descriptive analyses, we conduct a series of statistical analyses, using first difference and instrumental variables models, examining changes in attitudes towards non-traditional family behaviors, as well as changes in marital happiness and fertility intentions. Based on prior work suggesting that cohabitation is the linchpin in family change in Japan, using a reduced form random effects hazard model, we examine the age pattern of cohabitation and differentials in the probability of cohabiting. PUBLIC HEALTH RELEVANCE Major transformations in family behavior (marriage, cohabitation, divorce, childbearing and the use of child care centers) have occurred. The implications of these changes are profound, for both children (e.g. children growing up in single parent families) and the elderly (e.g. the changing ratio of workers and retirees). This project examines the processes, macro and micro, whereby such family behavior changes occur.